Adjust CSS to prevent scrollbars on message panel spinner

when clicking on permalinks/jump to first

src/skins/vector/css/matrix-react-sdk/structures/_RoomView.scss

@@ -96,6 +96,11 @@ limitations under the License.
     order: 2;
 }
 
+.mx_RoomView_body .mx_RoomView_messagePanelSpinner {
+    order: 2;
+    margin: auto;
+}
+
 .mx_RoomView_body .mx_RoomView_statusArea {
     order: 3;
 }
@@ -113,8 +118,6 @@ limitations under the License.
     max-width: 960px;
     margin: auto;
 
-    min-height: 100%;
-
     display: flex;
 
     flex-direction: column;